Here's an article that Australian and PGA Tour player Bradley Hughes posted over at the Advanced Ballstriking Forum. Thought it would be interesting to share.
Click the articles to enlarge them:
I would say that the sample size is a bit small for this to be a legitimately valid study and some other flaws that may hurt the study (particularly trying different blade irons vs. different GI irons).
But I still think it's a good ballpark estimate of what happens. The thing that it shows me that is important:
1. Mis-hits with GI's will tend to go longer.
2. Mis-hits with blades will tend to go straighter and have a much tighter dispersion.
Lastly, there's a big risk reward with the GI irons. I think there's a chance that if you mis-hit a GI iron you can still wind up hitting the occasional exceptional shot. However, if you mis-hit a GI iron you also risk hitting the shot that is far worse than mis-hitting a blade iron.